Re: [PATCH 3/3] btrfs: add helper function check device delete able

[Anand Jain <anand.jain@oracle.com>]

On 07/12/2018 03:43 PM, Nikolay Borisov wrote:
> 
> 
> On 10.07.2018 21:22, Anand Jain wrote:
>> Move the section of the code which performs the check if the device is
>> indelible, move that into a helper function.
>>
>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>> ---
>>   fs/btrfs/volumes.c | 49 ++++++++++++++++++++++++++++++-------------------
>>   1 file changed, 30 insertions(+), 19 deletions(-)
>>
>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>> index 59a6d8f42c98..feb29c5b44f6 100644
>> --- a/fs/btrfs/volumes.c
>> +++ b/fs/btrfs/volumes.c
>> @@ -1945,6 +1945,33 @@ static inline u64 btrfs_num_devices(struct btrfs_fs_info *fs_info)
>>   	return num_devices;
>>   }
>>   
>> +static struct btrfs_device *btrfs_device_delete_able(
> 
> Ugliest name ever! So this function is not really a predicate, rather
> it's used to fetch the struct btrfs_device * to delete. So a more
> becoming name would be:
> 
> btrfs_get_device_for_delete - though this a bit verbose.
> 
> I guess btrfs_can_delete_device is more suitable if you want to follow
> this predicate style. At the very least, though, the correct form of the
> adjective is deletable so it should be btrfs_device_deletable. But as I
> said this function is not really used as a predicate.

  Its a predicate, return of the device pointer is just a by-product.
  Will use btrfs_device_deletable().


>> +				struct btrfs_fs_info *fs_info,
>> +				const char *device_path, u64 devid)
>> +{
>> +	int ret;
>> +	struct btrfs_device *device;
>> +
>> +	ret = btrfs_check_raid_min_devices(fs_info,
>> +					   btrfs_num_devices(fs_info) - 1);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +
>> +	ret = btrfs_find_device_by_devspec(fs_info, devid, device_path,
>> +					   &device);
> 
> Not really related to this patchset, but I think the whole
> btrfs_find_device_by_devspec -> btrfs_find_device_missing_or_by_path
> could be simplified by making those functions return a pointer to
> btrfs_device rather than an int error value. That way you eliminate the
> ugly "argument as return value" convention.

  I agree with you. This is just a fist set of cleanup.

Thanks, Anand


>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +
>> +	if (test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state))
>> +		return ERR_PTR(BTRFS_ERROR_DEV_TGT_REPLACE);
>> +
>> +	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) &&
>> +	    fs_info->fs_devices->rw_devices == 1)
>> +		return ERR_PTR(BTRFS_ERROR_DEV_ONLY_WRITABLE);
>> +
>> +	return device;
>> +}
>> +
>>   int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
>>   		u64 devid)
>>   {
>> @@ -1958,25 +1985,9 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
>>   
>>   	mutex_lock(&uuid_mutex);
>>   
>> -	num_devices = btrfs_num_devices(fs_info);
>> -
>> -	ret = btrfs_check_raid_min_devices(fs_info, num_devices - 1);
>> -	if (ret)
>> -		goto out;
>> -
>> -	ret = btrfs_find_device_by_devspec(fs_info, devid, device_path,
>> -					   &device);
>> -	if (ret)
>> -		goto out;
>> -
>> -	if (test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) {
>> -		ret = BTRFS_ERROR_DEV_TGT_REPLACE;
>> -		goto out;
>> -	}
>> -
>> -	if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) &&
>> -	    fs_info->fs_devices->rw_devices == 1) {
>> -		ret = BTRFS_ERROR_DEV_ONLY_WRITABLE;
>> +	device = btrfs_device_delete_able(fs_info, device_path, devid);
>> +	if (IS_ERR(device)) {
>> +		ret = PTR_ERR(device);
>>   		goto out;
>>   	}
>>   
>>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>